Bag opening machine



March 24, 1970 A. F. PETERSON 3,501,893

BAG OPENING MACHINE Filed Jan. 8, 1968 v 6 Sheets-Sheet 1 INV ENT OR 50AXE! f. Ptrewswv March 24, 1970 A. F. PETERSON BAGDPENING MACHINE 6Sheets-Sheet 2 Filed Jan. 8, 1968 7 u v y a 4- 1 J 2W0. 4 3\ Lil. I 4 5a 54. w M u w 9 7 a M 10 6 N 4 aw 1/ 5 f 4 M fi a 5 Fm z a w w a 3 171 3MM, A M

Axn 1"." PETERSON (2 BY Q.

ATTORNEY March 24, 1970 A. F. PETERSON BAG OPENING MACHINE 6 SheetsSheet4 Filed Jan. 8, 1968 INVENTOR AXE; F P'l'E/PSON BY gwvhannmq ATTORNEYMarch 24, 1970 A. F. PETERSON 3,

BAG OPENING MACHINE Filed Jan. 8, 1968 v 6 Sheets-Sheet 6 INVENTOR AXELF. Fifi-RSON BY QMW ATTORNEY United States Patent US. Cl. 53-190 ClaimsABSTRACT OF THE DISCLOSURE The invention discloses a bag openingapparatus for use with fiat folded bags having pleated walls. The deviceincludes a bag filling guide, and a pair of arms pivoted on parallelplanes on opposite sides of said guide. The arms are provided withextensible and retractable end portions provided with bag engagingsuction cups connectable to a source of partial vacuum. The arms areswingable from a substantially vertical position through somewhat morethan ninety degrees to a position adjacent to the filling guide and onopposite sides thereof. When in vertical position the suction cups ofone arm engage the uppermost bag of a series of superimposed bags. Theextensible end of said one arm retracts, and the arms swing in unisonuntil the bag is engaged by the suction cups of the other arm. Theextensible end of the other arm retracts to open the big. When carriedto position adjacent the filling guide the sides of the bag are clampedfor filling.

This invention relates to an improvement in bag opening machine anddeals particularly with an apparatus capable of picking up a bag from asupply stack, swinging it into upright position, opening the upper endof the bag, and holding the bag in opened position for a predeterminedtime period before releasing it.

Some years ago the filling of bags with flowable material of one type orthe other was a manual operation. The operator picked up a bag from asupply pile, opened it up and placed it beneath a filling mechanism,operated the filling mechanism to fill the bag, and carried or otherwisemoved the filled bag to a bag closing mechanism such as a sewingmachine, a stapler, or the like. With the increase in cost of labor,such a manual operation became somewhat impractical, and as a result,machines of one type or the other were developed to accomplish thedesired result. The present invention lies in the provision of anapparatus for packing up a bag made of paper or other suitable materialfrom a vertical stack or pile of horizontal bags, swinging the bag intovertical position and simultaneously opening the bag by drawing theopposite walls of the bag apart, and holding the bag in an elevatedposition during the filling operation. As soon as the bag is released,the bag is moved out of filling position and the cycle of operationrepeats.

A feature of the present invention resides in the provision of a deviceincluding suction arms swingable from a generally upright position inwhich suction cups on one of the arms engage the uppermost bag of astack of bags through an angle of somewhat more than 90 degrees to aposition adjoining a filling spout. As one suction arm carries the bagfrom one position to another, a second suction arm engages the oppositeside of the bag, the two suction arms drawing the bag into open positionas it moves into filling position. Means are provided for pivoting thearms on opposite sides of the bag in unision during the bag openingoperation.

A feature of the present invention resides in a device of the typedescribed including a pair of clamping members which enter the openupper end of the bag as it reaches filling position. As the upwardmovement of the bag stops, means are actuated to move the clamping3,501,893 Patented Mar. 24, 1970 ice means against the bag to hold thebag securely during the filling operation. After a predetermined timeperiod, the clamping means is released allowing the bag to drop unto asuitable conveyor and permitting the suction arms to return to startingposition.

A further feature of the present invention resides in the provision of asuction arm including two tubular telescoping members one of which isprovided at its end with one or more parallel suction cups. The othertubular member is connected to a source of partial vacuum. As thesuction arms swing down toward vertical position, the portion of thesuction arm bearing the suction cup slides partially out of the tubularmember connected to the vacuum source to elongate the arm. As soon asthe suction cups engage the surface of a bag, the suction acts toretract the slidable tubular member into the pivoted tubular member,raising the bag from the stack into position to be opened.

A further feature of the present invention resides in the provision of aparticular type of suction cup which has been found particularly usefulin the combination. The suction cup includes a relatively inflexibletube to which is secured a highly flexible skirt which is preferablycorrugated so as to readily contract in length. The flexible skirt isbrought into contact with the surface of the bag, and immediatelyconforms to the shape of the bag. When the skirt is engaged to the bag,the suction acts to contract the skirt until the surface of the bag isdrawn against the end of the relatively inflexible inner tube. With thisarrangement, the bags are readily picked up while at the same time themovement of the bag is controlled by engagement of the wall of the bagagainst the rigid inner tube once the bag has been picked up.

These and other objects and novel features of the present invention willbe more clearly and fully set forth in the following specification andclaims.

In the drawings forming a part of the specification:

FIGURE 1 is a front elevational view of the bag opening apparatusshowing the general arrangement of parts therein.

FIGURE 2 is a perspective detail of the bag lifting arm showing thelatch arrangement used to hold the arm in inoperable position when thedevice is not in use.

FIGURE 3 is a perspective detail of one arrangement of suction cupswhich may be used on the bag lifting arm.

FIGURE 4 is a vertical sectional view through one of the suction cupsillustrated in FIGURE 3 of the drawlllgS.

FIGURE 5 is a diagrammatic top plan view of the bag opening mechanism,showing the general arrangement of parts therein.

FIGURE 6 is a perspective view showing one of the bag lifting arms.

FIGURE 7 is a sectional view through a portion of the bag lifting arm.

FIGURE 8 is a fragmentary detail showing the manner in which the two bagengaging arms are moved in unison.

FIGURE 9 is a fragmentary view showing the cylinder employed forrotating the arms in unison.

FIGURE 10 is a fragmentary detail showing the means for operating thebag clamping means to hold the bag in open position during filling.

FIGURE 11 is a vertical sectional view through the means for clampingthe bag in open position during the filling operation.

FIGURE 12 is a fragmentary detail illustrating the mounting of the bagopening arm.

FIGURE 13 is a diagrammatic view showing the general position of the baglifting and opening arms at the beginning of a cycle of operation.

FIGURE 14 is a diagrammatic view of the position of the arms as the bagis lifted into position to be engaged by both of the opposed arms.

FIGURE 15 is a diagrammatic view showing the position of the arms whenthe bag is in fully elevated position.

FIGURE 16 is a side elevational view of the bag opening arm in operableposition.

FIGURE 17 illustrates diagrammatically a portion of the pneumaticsystem.

FIGURE 18 is a diagrammatic view showing the air pressure and airsuction lines and the valves used to operate the same.

FIGURE 19 is an enlarged detail of the end of the bag lifting armsshowing the suction cups in elevated position.

FIGURE 20 is a view similar to FIGURE 19 but showing the suction cupsafter they have engaged the surface of a bag.

FIGURE 21 is an enlarged sectional detail showing the manner in whichthe bag may flex relative to the suction cup arrangement.

The bag opening apparatus is best shown in general in FIGURES 1 and 5 ofthe drawings. The device is indicated in general by the letter A, andincludes a pair of front posts or standards and 11, and a pair ofsimilarly spaced rear posts or standards 12 and 13. The upper end of thestandards 10 and 11 are connected by a horizontal connecting member 14,and the upper ends of the posts 12 and 13 are connected by a parallelhorizontal connecting member 15. The connecting members 14 and 15 areconnected by cross-members 16 and 17. The standards 10 and 11 may alsobe connected by other supporting frame members, as may also be thestandards 12 and 13.

A horizontal connecting member 19 may connect the columns 12 and 13, andvertical angle members 20 and 21 may extend upwardly from the lowerframe member 19 to the upper frame member 15. A generally rectangularframe 22 extends laterally to one side of the columns 11 and 13 as isbest illustrated in FIGURE 5. The rectangular frame member 22 includes afront frame member 23, a rear frame member 24, and a side connectingframe member 25. As indicated in FIGURE 1 of the drawings the frame 22is supported by suitable supporting legs 26.

The front and rear columns 11 and 13 are provided with bearings 29 whichsupport a horizontal shaft 30 (see FIGURE 2). The shaft 30 pivotallysupports the bag lifting arms 31 and function to swing the arm mechanism31 through somewhat more than 90 degrees. A similar pair of bearings .32(see FIGURE 1) are mounted upon the vertical standards or columns 10 and12 to support a shaft 33 in opposed relation to the shaft 30. The shaft33 supports the arm mechanism which is indicated in general by thenumeral 34 and which functions to open up the bag B which is lifted bythe suction arm 31.

A platform or table 36 is supported within the frame 22. Vertical rods37 are connected to the platform 36 near the corners thereof, and therods 37 are slidable in sleeves 39 supported by vertical brackets 40mounted upon the frame 22. The platform 36 is supported by a pair ofcables 41 which are secured to opposite sides of the plaform 3'6 and aresecured in their opposite ends, as indicated at 42, to the frame 22. Apair of vertical cylin- :lers 43 are mounted upon the frame members 23and 24 on opposite sides of the platform 36 near the center thereof, andeach cylinder contains a piston identified in FIGURE 18 by the numeral44 and to which a piston rod 45 is attached. The pulley 46 ismounted ina clevis 47 at the upper end of each piston rod 45. The cable 41 extendsfrom the platform 36, over the pulley 46 and is anchored to the frame at42. Accordingly, as the piston 44 is forced upwardly in each of thecylinders 43, the elevations of the pulley 46 increases, and theplatform 36 is raised. The purpose of this arrangement is to maintainthe uppermost bag B on the platform 36 at a substantially equal level.

As indicated in FIGURE 2 of the drawings, a clamping bracket 49 issecured to the pivot rod 30. A radially extending arm 50 is secured tothe bracket 49 and supports a right angularly extending bracket 51. Atubular member 52 forming the upper pivotal end of the bag lifting armis clamped in the bracket 51. A second clamping bracket 53 is secured tothe tubular member 52 below the position of the bracket 51 when the baglifting arm is in generally vertical position. The bracket 53 isprovided with a laterally extending arm 54 supporting a rod 55 whichextends through the arm 50. The rod 55 is provided with adjustable stopmeans 56 for a purpose which will be later described.

A second tubular member 57 is slidably supported within the tubularmember 52, and supports a yoke 59 designed to support suction cups of atype which will be later described. The clamping bracket 53 supports alaterally extending bracket 60 which pivotally supports a locking arm61. The locking arm 61 is provided with an angularly turned lower end 62which is engageable beneath the yoke 59 of the lower tubular member 57.The arm 61 is provided with an enlarged upper end 63 which may bepivotally engaged by a locking lever 64 mounted upon a bracket 65adjustably secured to the upright 11.

The arrangement is such that when the latch member 64 is in one positionshown in dotted outline in FIG- URE 2, the hook end 62 of the arm 61 isout of the path of movement of the yoke 59 of the tubular member 57,allowing the yoke to drop into contact with the surface of the bags B.When the latch 64 is in its outer extreme position, the arm 61 movesinto the position shown in dotted outline in FIGURE 2 of the drawings,engaging the yoke 59 and preventing the tubular member from dropping. Asindicated in FIGURE 2, the spring 66 normally draws the hook end '63toward one extreme position. A lug 67 on the latch 64 holds the latch ineither extreme position, the latch being manually operable.

The means for operating the bag lifting arm 31 is best illustrated inFIGURES 1 and 9 of the drawings. A crossmember 69 connects the rearcolumn 13 with the upright 21. A pneumatic cylinder 70 is pivotallyconnected at 68 to the cross-member 69. A piston 71 (see FIGURES 9 and18) is connected to a connecting rod 72 leading to a crank arm 73mounted upon the shaft 30. When the piston 71 is moved upwardly in thecylinder 70, the crank arm 73 is rotated in clockwise direction rotationof the arm 30. The cylinder 70 and its piston 71 are so proportionedthat the bag lifting arm 31 is pivotal from a generally verticalposition in which the suction cups engage the uppermost bag B, to theposition illustrated in full lines in FIGURE 1 of the drawings. In otherwords, in the arrangement illustrated the shaft 30 is rotated through anangular distance of somewhat more than 90 degrees by the piston 71 andthe cylinder 70.

With reference to the FIGURES 1 and 8 of the drawings, means areprovided for rotating the shafts 30 and 33 in unison. As indicated inFIGURE 1, a sprocket 74 is mounted upon the shaft 30. A cooperablesprocket 75 is mounted upon a shaft 76. The shaft 76 is supported by abracket 77 in fixed relation to the frame. The sprockets 74 and 75 areconnected by a chain 79, the tension of which is adjusted by means of anidler sprocket 80. A parallel shaft 81 supported by a bracket 78supports a sprocket 82 connected to the shaft 33 by means of a chain 83,the tension of which is adjusted by an idler sprocket 84. As indicatedin FIGURE 5 of the drawings the shafts 76 and 81 support intermeshinggears 86 and 87 which cause the shafts 76 and 81 to move in unison inopposite directions. As a result, the clockwise movement of the shaft 30controlling the position of the bag pickup arm unit 31 causes acounter-clockwise pivotal movement of the shaft 33 supporting the bagopening arm unit 34.

As is indicated in FIGURES 6 and 7 of the drawings, a bracket 90 ismounted upon the shaft 33 and includes a radially extending arm 91supporting a clamping bracket 92 which is in right angular relation tothe clamping bracket 90. The bracket 92 includes a tubular arm member 93which is clamped in fixed relation to the shaft 33. A second tubularmember 94 is slidable in the tubular member 93 for movementlongitudinally thereof. As indicated in FIGURE 7 of the drawings, a seal95 is interposed between the end of the tubular member 93 and thetubular member 94. A second seal 96 is interposed between the upper endof the tubular member 94 and the pivotal tubular member 93. Thus whenthe interior of the tubular member 93 is subjected to partial vacuum,the interior of the tubular member 94 is similarly subjected to partialvacuum.

A yoke 97 is secured to the lower end of the tubular member 94. The yoke97 is hollow and tubular, and the actual construction of this portion ofthe apparatus is best illustrated in FIGURES 19 and 21 of the drawings.It should be understood that the yoke 97 is identical to the yoke 59mounted upon the tubular member 57 of the bag pickup unit 31.

As indicated, the yoke 97 is substantially inverted U-shaped in formterminating in end portions 99 which are on a substantially commonplane. Flexible resilient corrugated sleeves 100 are provided with arelatively large diameter open end 101, and a relatively small diametercylindrical attaching sleeve 102 which encircles the yoke 97. Thearrangement is such that when the corrugated suction cups 100 are intheir normal relaxed position as indicated in FIGURE 19 of the drawings,the open ends 101 of the cups extend substantially beyond the ends 99 ofthe yoke 97. The corrugated flexible nature of the cups or sleeves 100permit the open end to readily adapt themselves to the surface of thebag B being engaged. On the other hand, when the open ends 101 of thecollapsible sleeves 100 are subjected to partial vacuum and are closedby a surface of the bag B, the sleeves 100 will collapse until the end99 of the yoke 97 are in contact with the surface of the bag B. Asindicated in FIGURE 2l of the drawings, once the bag B has been engagedand drawn against the end 89 of the yoke 97, the surface of the bag maybend to permit the bag B to assume a considerable angularity relative tothe collapsible sleeve portion 100 of the suction cups.

The tubular members 52 and 57 operate in a manner similar to thetelescoping tubes 93 and 94. As long as the suction cups on the yoke 59and the yoks 97 are open to atmosphere, and when the tubular members arein generally vertical position as indicated in dotted outline in FIGURE1 of the drawings, the suction cup supporting yokes drop by gravity intoextended position. The degree of extension of the tubular members 52, 57is limited by the rod 55 and the adjustable nut 56. The degree ofextension of the tubular members 93, 94 is limited by the rod 103 whichextends through a lug 104 on the tubular member 94, and through alignedapertures in lugs 105 and 106 on the tubular members 93, the limit ofmovement of the rod 103 being adjusted by an adjustment nut or collar107. As is indicated in FIGURE 1 and FIGURE 6 of the drawings, flexiblesuction hoses 109 and 110 are connected to the tubular members 52 and 93respectively to withdraw air therefrom. Thus when the bag pickup armunit 31 pivots into substantially vertical position, and the yoke 59drops until the suction cups 111 mounted upon the yoke 59 engages theuppermost bag B, the tubular member 57 is automatically retracted intothe tubular member 52 raising the uppermost bag as will be described.

As is indicated in FIGURE 5 of the drawings, a pair of forwardly andrearwardly extending supports 112 and 113 extend between the top framemembers 14 and 15 and support the brackets 77 and 78 and a pair ofparallel brackets 114 and 115. Brackets 116 and 117 extend downwardlyfrom the brackets 114 and 115. The brackets 116 and 117, as indicated inFIGURE 10 of the drawings, support opposed inwardly extending arms 119and 120 which support fixed clamping members 121 and 122. The fixedclamping members 121 and 122 provide abutment against which the oppositeouter sides of the bag B are clamped during the filling operation.

The bag clamping apparatus is perhaps best illustrated in FIGURES l0 and11 of the drawings. As'indicated in FIGURE ll, a filling hopper 123 issupported above the bag B when the bag is in elevated position. A pairof clamping plates 124 and 125 are pivotally supported upon shaft 126and 127 on opposite sides of the hopper 123, the clamping plates beingattached to the shafts 126 and 127 in order to move in conjunctiontherewith. FIGURE 11 of the drawings indicate the bag B in partiallyraised position, the bags being moved in the direction of the arrow 129.When the bag is in fully elevated position, it engages between thefriction surfaces 130 and 131 of the member 119 and 120 and is held inthis position by the outward swing of the clamping plates 124 and 125.In order to accomplish the desired result, the mechanism indicated inFIGURE 10 of the drawings is provided, the clamping blades 124 and 125being indicated in dotted outline in this figure. A pair of crank arms132 and 133 are mounted upon the parallel shafts 127 and 126 and rotatein unison therewith. A hydraulic piston cylinder unit 134 is mountedbetween the arms 132 and 133. The piston-cylinder unit 134 includes acylinder 135 having a fixed arm 136 on one end thereof pivotallyconnected at 137 to the arm 132. A piston 139 in the cylinder 135 isconnected to a piston rod 140 which is pivotally connected at 141 to thearm 133. As is obvious, movement of the piston 139 to the right in thecylinder 135 will rotate the shaft 126 in a counter-clockwise direction,and rotate the shaft 127 in a clockwise position, acting to clamp thewalls 142 and 143 of the bag B against the fixed abutments 121 and 122.

In order to insure uniform movement of the arms 132 and 133, a pair ofgears 144 and 145 are mounted upon parallel pivots 146 and 147. Crankarms 150 and 151 are mounted upon the pivots 146 and 147 to rotate inunison therewith. Links 152 and 153 are pivotally connected at 154 and155 respectively to the ends of the crank arms 150 and 151, and arepivotally connected at their other ends as indicated in 156 and 157 tothe crank arms 132 and 133. The crank arm 132 is parallel to the crankarm 150, and the crank arm 133 is parallel to the crank 151. As aresult, upon actuation of the piston 139 in the cylinder 135, theclamping plates 124 and 125 are pivoted uniformly against the abutments130 and 131 in order to clamp the bag in an open position.

The pneumatic system for operating the apparatus is best illustrated inFIGURE 18 of the drawings. The letter F designates a pressure conduitleading from a source of air under pressure. The letter V indicatesconnections to a source of partial vacuum.

The pressure conduit P is connected to a limit switch 160 which isnormally open. Air under pressure may flow through the conduit 161, thecheck valve 162 and conduit 163 to the lower end of the cylinder 43 toraise the piston 44. The limit switch 160 is provided with a plunger orfeeler 164 which rests upon the surface of the uppermost bag B on theplatform 36. When the bags B are at the desired elevation, the plungeror feeler 164 is raised, closing the conduit to the cylinder 43 andpreventing further raising of the platform 36 until the level of thebags B lowers to the point wherefurther elevation is required.

An exhaust valve 165 is provided in an exhaust line 166 connected to thelower end of the cylinder 43. When it is desired to lower the platform3-6 in order to place additional bags on the platform, the manuallyoperable plunger 167 may be lowered to connect the conduit 166 toatmosphere, thereby allowing the piston 44 and its piston rod 45 to dropto the lowermost position.

The pressure line P also extends to an air switch 170 which is normallyclosed but which may be held by suitable means not illustrated in thedrawings in an open position. From the air switch 170, the air may flowthrough conduits 171 and 172 to valves 173 and 174 controlling the flowof vacuum through the bag pickup arm unit 31 and to the bag opening unitwhich may be indicated in general by the numeral 175. When the manuallyoperable valve 170 is in closed position, the bag pickup arm 31 and thebag opening arm unit 175 are inoperative. However, when the air switch170 is open, the valve elements 176 and 177 are moved into position tosubject the interiors of the cylinders 52 and 93 respectively to partialvacuum from the vacuum line V. The letter M indicates conduits oropenings which extend to atmosphere.

The pressure conduit P is also connected by a conduit 181 to an airswitch 182 controlled by a member 183 which is operated by the relativemovement of the telescoping members 52 and 57. When the members 52 and57 have elongated sufliciently to engage the uppermost bag B on theplatform 36, the member 183 opens the valve 182 to direct the flow ofair through the conduit 184 to a valve 185. The valve 185 normallydirects air through a conduit 186 to the upper end of the cylinder 70,holding this cylinder in a retracted position. However, when air isintroduced into the valve 185 through the conduit 184, the piston 187 ismoved to the left as viewed in FIGURE 18, connecting the air conduit Pwith the conduit 189 leading to the lower end of the cylinder 70, andacting to raise the piston 170. This action acts to rotate the arms 31and 175 through a pre-determined angular distance.

Most of the elements of the apparatus are controlled by rotation of theshafts from one extreme position to another. The conduit 184 isconnected by a conduit 190 to a valve 191 which is normally closed.However, when the arm 31 is swung into the position shown in full linesin FIGURE 1 of the drawings, a cam means 192 act upon the valve plunger193 opening the conduit 190 to atmosphere, and allowing the valve 185 toreturn to its original position due to the presence of the operatingspring 194.

A valve 195 of the normally closed type is connected by a conduit 196 tothe pressure line P. The valve 195 includes a piston 197 having a pistonrod 199 controlled by a cam 200 on one of the operating shafts such asthe shaft 30. Thus when the arms 31 and 34 are moved into their extremeupper positions, the cam 200 opens the valve 195 to perform a functionwhich will be described.

The pressure line P is also connected to a valve 201 which normallydirects air through a conduit 202 to the end of the cylinder 134 tendingto retract the piston 139 in the cylinder. The conduit 203 is normallyconnected to atmosphere from the opposite end of the cylinder.

When the air switch or valve 195 is actuated to open the valve, a flowof fluid is provided from the conduit 196 through the conduit 205 to theend of the cylinder valve 201 forcing the valve element 206 to the leftas viewed in FIGURE 18. When in this position, the air from the conduitP flows through the conduit 203 to the cylinder 135 forcing the piston139 in the direction to extend the distance between the pivots 137 and141. This action causes the clamping member 124 and 125 to clamp the bagB against the friction surfaces 130 and 131 of the abutments 121 and122.

The conduit 205 which leads from the valve 195 to the air controlledvalve 201 includes a time delay device 207 which retains the cylinderunit 134 in extended position for a predetermined period of time beforereleasing the air and permitting the clamping devices 124 and 125 torelease the bag.

As is obvious from FIGURE 5 of the drawings, a conveyor 210 extendsbeneath the bag supported by the clamping arms 124 and 125, and theconveyor may act to convey the bag from beneath the clamps after theclamps have been released. The conveyor 210 is of the endless type andis operated by the drive motor 211.

FIGURES 12 through 17 of the drawings show a structure similar to thatdescribed in the previous description with the exception of the bagopening arm structure. The arrangement shown in these figures serves thesame purpose as the structure previously described. However, thisstructure permits the apparatus to return to its original or startingposition somewhat more quickly than the previous structure, and isillustrated for this purpose.

FIGURE 12 of the drawings discloses a bracket 180 secured to the shaft33 and supporting an arm 181 secured to the bracket for rotation inconnection therewith. The arm 181 supports a pair of spaced brackets 182and 183, between which is supported a double acting pneumatic cylinder184. The purpose of this arrangement will be described.

The cylinder 184 includes a piston which operates a piston rod 185. Aright angular bracket 186 includes one arm 187 which is slidablysupported by the bracket 180, and includes a right angular arm 189supporting a bracket 190. These arms 193 and 194 are encircled by vacuumcups 100 of the type which is previously described.

FIGURES 13 through 16 of the drawings are designed to diagrammaticallyillustrate various positions of the cylinder 184 and the bag pickupmechanism 31 during the operating cycle. FIGURE 13 of the drawings showsthe tubular member 57 of the bag pickup unit 31 in extended position andwith the suction cups thereupon engaging the uppermost bag of a seriesof bags B. From the position illustrated in FIGURE 13, the suctionwithin the tubular member 52 will retract the tubular member 57 into thecylinder 52, raising the uppermost bag from the stack.

FIGURE 14 of the drawings shows the bag pickup cylinder 31 swung throughan angle of somewhat less than degrees and the piston 185 of thecylinder 184 projected from the cylinder so that the suction cupsthereupon are in engagement with the side of the bag B opposite thatengaged by the suction cups 100 of the pickup arm 31. When inapproximately the position shown in FIGURE 14, the piston within thecylinder 184 is actuated to retract the piston arm 185 into the cylinder184, thus spreading the sides of the bag B apart to open the bag.

FIGURE 15 of the drawings shows the bag pickup unit 31 and the cylinder184 in their opposite extreme positions from those shown in FIGURE 13.In this position, the bag B has been spread open and positioned inwardlyof the fixed clamping members 121 and 122. This view also illustratesmovable clamping plates 124 and clamping the bag in position.

FIGURE 17 shows a simple hydraulic circuit for operating the piston 195on the piston rod within the cylinder 184. The pressure line P isconnected by a conduit 196 to a normally closed air switch 197controlling the flow of air through the conduit 199 to pneumatic valve200. The pressure line P is also connected by a conduit 201 to thevalve, and the air under pressure normally flows through a conduit 202to the cylinder 184 in the direction to retract the piston and thepiston arm 185. The opposite end of the cylinder 184 is connected by aconduit 203 to the valve 200 and the upper end of the cylinder isnormally subjected to atmosphere. The air switch 197 is actuated by cammeans 204 which first opens the air switch to the conduit 199 to movethe position of the valve 200 and to direct air under pressure to theupper end of the cylinder 184 as viewed in FIGURE 17, and to connect thelower end of the cylinder to atmospheric pressure. Further movement ofthe air switch 197 by the cam 204 connects the pressure line 196 toatmosphere, reversing the position of the 9 valve 200 and quicklyretracting the piston 195 and piston rod 185 in the cylinder 184.

In accordance with the patent statutes, I have described the principlesof construction and operation of my improvement in bag opening machines,and while I have endeavored to set forth the best embodiment thereof Idesire to have it understood that changes may be made within the scopeof the following claims without departing from the spirit of myinvention.

I claim:

1. A bag opening device including:

a filling guide,

a pair of arms pivotally supported on parallel pivots on opposite sidesof said filling guide,

means pivoting said arms in unison from a generally vertical positionthrough a generally horizontal position,

means supporting a supply of bags in substantially horizontal positionbeneath one of said arms when in said vertical position, each of saidarms includes an extensible and retractable end portion includingsuction cups engageable with said bag,

the suction cups of said one arm being engageable with the uppermost bagof said supply when in said substantially vertical position, wherebypivotal movement of said arms will swing the bag engaged into the pathof movement of the suction cups on the other of said arms,

means retracting the retractable end portion of said other arm to drawthe opposite sides of said bag apart,

said arms moving said bag into position to receive material passing saidfilling guide.

2. The structure of claim 1 and including means for retracting saidretractable end of said one arm upon engagement of said suction cups onsaid rectractable end with the uppermost bag of said supply.

3. The structure of claim 1 and including means actuated by pivotalmovement of said arms into material receiving position for clamping saidbag walls in open position.

4. The structure of claim 1 and including fixed clamping members onopposite sides of said bag between which said bag is moved by said arms,

movable clamping means inwardly of said fixed clamping members andextending into said bag when in material receiving position, and

means actuated by movement of said arms into position to move said baginto material receiving position to move said movable clamping meanstoward said fixed clamping members.

5. The structure described in claim 1 and in which said arms aretubular, and including a source of partial vacuum connected to theinterior of said arms and through said .arms to said suction cups.

. 6. The structure of claim 5 and in which said source of partial vacuumcauses retraction of the retractable arm ends when said suction cupsthereupon are closed by engagement with the bag.

7. The structure of claim 1 and in which said arms are tubular, andincludes a source of partial vacuum connected thereto communicating withsaid suction cups thereon, and in which suction from said partial vacuumsource retracts said retractable end of said one arm upon engagementwith said uppermost bag.

8. The structure of claim 7 and including a pneumatic cylinderconnecting the other said arm to its extensible end, and means foroperating said pneumatic cylinder to extend and retract said extensibleend.

9. The structure of claim 1 and in which said arms are tubular andincluding a source of partial vacuum connected to said arms andcommunicating with said suction cups and including means actuated bymovement of said arms into material receiving position to disconnectsaid source of partial vacuum from said arms.

10. The structure of claim 9 and including clamping means engageablewith opposite sides of said open bag in material receiving position, andmeans operable by movement of said arms to actuate said clamping meansto clamp the bag.

References Cited UNITED STATES PATENTS 3,208,194 9/1965 Johnson et a1.53-190 2,814,488 11/1957 Kipers 53-386 X 3,430,409 3/1969 Manfredonia etal. 53-190 X 3,169,354 2/1965 Bliss et al. 5361 TRAVIS S. MCGEHEE,Primary Examiner H. M. CULVER, Assistant Examiner US. Cl. X.R, 533 86

